Using the PhoneWakeState I was able to use some sensors. So I have tried to insert code to send SMS (some idea, why not...). The problem I had was that the SMS was only sent when the screen was ON again.
Using PhoneWakeState I was able to keep the screen on as it should be but was never able to activate the screen. Please does it exist a way to activate the screen when needed by a service ? Using Reflection perhaps ?
It is fixed My stupid mistake was to dim twice. I was lost between code module and the service one... KeepAlive(true) works perfectly and needs no more.